Tests for a difference in timing of physiological response between two brain regions measured by using functional magnetic resonance imaging

Summary.  Functional magnetic resonance imaging (FMRI) measures the physiological response of the human brain to experimentally controlled stimulation. In a periodically designed experiment it is of interest to test for a difference in the timing (phase shift) of the response between two anatomically distinct brain regions. We suggest two tests for an interregional difference in phase shift: one based on asymptotic theory and one based on bootstrapping. Whilst the two procedures differ in some of their assumptions, both tests rely on employing the large number of voxels (three-dimensional pixels) in non-activated brain regions to take account of spatial autocorrelation between voxelwise phase shift observations within the activated regions of interest. As an example we apply both tests, and their counterparts assuming spatial independence, to FMRI phase shift data that were acquired from a normal young woman during performance of a periodically designed covert verbal fluency task. We conclude that it is necessary to take account of spatial autocovariance between voxelwise FMRI time series parameter estimates such as the phase shift, and that the most promising way of achieving this is by modelling the spatial autocorrelation structure from a suitably defined base region of the image slice.     

Religion as a Meaning System: Policy Implications for the New Millennium

The development of social policy related to religion has received increasing focus in recent years, yet psychology continues to play a relatively minor role in this important domain. In the current article, religion's positive and negative influences as a meaning system on individual, community, and societal well-being are delineated. The challenges facing psychology in contributing to public policy development in the religious arena are examined, challenges that stem from profound differences in the meaning systems of religion, government, and psychology. These challenges notwithstanding, a number of different pathways in the domains of applied research, community practice, and policy development are delineated through which psychology can help to maximize positive, and minimize negative, outcomes in the religion and social policy arena.     

Slack-variable models versus Scheffé's mixture models

Slack-variable models are compared against Scheffé's polynomial model for mixture experiments. The notion of model equivalence and the use of various diagnostic measures provide effective tools in making such comparisons, particularly when the experimental region is highly constrained. It is demonstrated that the choice of the best fitting model, through variable selection, depends on which mixture component is selected as a slack variable, and on the size of the fitted model. In addition, the equivalence of two well-known representations of a complete mixture model is shown to be valid. Two numerical examples are presented.     

THE McMASTER FAMILY ASSESSMENT DEVICE: RELIABILITY AND VALIDITY*

This paper reports a series of studies investigating the reliability and validity of the McMaster Family Assessment Device (FAD). The results indicated that the FAD has: (a) adequate test-retest reliability, (b) low correlations with social desirability, (c) moderate correlations with other self-report measures of family functioning, and (d) differentiates significantly between clinician-rated healthy and unhealthy families. Cut-off scores for identifying healthy and unhealthy families also were developed which have adequate sensitivity and specificity. Additionally, the relationships between the FAD, Family Unit Inventory, and FACES-II suggests that the cohension and adaptability scales from the FACES-II have a linear relationship with health/pathology.     

The teaching of the concepts of statistical tests of hypotheses to non-statisticians

The logic underlying the formulation of statistical tests of hypothesis can be counterintuitive for the non-mathematician, e.g. to test whether two treatments are different, why suppose they are equal? When introducing the topic of hypothesis testing, it is easy to present the formal fiamework for the testing procedure without explaining the logic behind it. In courses for statisticians, one may often (unjustifiably) rely on the understanding of probability concepts as a foundation for understanding statistical inference, but in courses taught to non-statisticians where there is minimal discussion of probability, it is essential that explanations must be based on concepts the students can readily understand. The method proposed here for teaching the concept of hypothesis testing makes an analogy to the judicial system, whereby a person is assumed innocent until sufficient evidence warrants a verdict of guilty. Analogies for the different elements of statistical tests are presented and discussed, together with a classroom fiamework for discussion of statistical tests.     

Semiparametric mixture models and repeated measures: the multinomial cut point model

Summary.  Suppose that we have m repeated measures on each subject, and we model the observation vectors with a finite mixture model.  We further assume that the repeated measures are conditionally independent. We present methods to estimate the shape of the component distributions along with various features of the component distributions such as the medians, means and variances. We make no distributional assumptions on the components; indeed, we allow different shapes for different components.     

Alternative Bases of Source Selection

Dans un article précédent nous avons présenté les résultats d'une expérience concue pour mettre à l'épreuve certaines prédictions d'une théorie formelle de la relation interpersonnelle en ce qui à trait a l'émergence des anticipations de conduite lorsque plusieurs sources d'évaluation de cette conduite anticipee sont disponibles a un individu, Dans cet article nous formulons deux alternatives additionnelles qui sont théoriquement plausibles, les multiples prédictions em-piriques qu'elles engendrent, et une évaluation de ces trois formulations particu-lières à la lumière des données existantes. De ces trois formulations, seule la première est appuyee par nos donnees empiriques. Voici de quelle manière elle s'exprime: mis en présence de plusieurs sources d'évaluation l'individu intègre l'ensemble des éléments de l'évaluation plutot que de (a) choisir seu-lement la meilleure source disponible, ou (b) d'utiliser la source la moins bonne comme une ?source négative?, ou encore de se servir de l'évaluation de celui dont l'exactitude ne peut etre mise en doute. In an earlier paper we reported the results of an experiment designed to test certain predictions of a formal theory of interpersonal behaviour concerning the formation of performance expectations when multiple sources of performance evaluation were available to an individual. In this paper we present two additional theoretically reasonable alternative formulations, the different empirical predictions derivable from them, and an evaluation of the three formulations in the light of the existing data. Of the three, only the original formulation received clear empirical support. This formulation holds that when faced with multiple sources of evaluation, the individual combines the evaluations received, rather than (a) selecting only the best source available, or (b) using the lower source as a “negative source,” or someone whose evaluation is so likely to be incorrect as to provide an accurate measure of the correct evaluation.     

Category Distinguishability and Observer Agreement

It is common in the medical, biological, and social sciences for the categories into which an object is classified not to have a fully objective definition. Theoretically speaking the categories are therefore not completely distinguishable. The practical extent of their distinguishability can be measured when two expert observers classify the same sample of objects. It is shown, under reasonable assumptions, that the matrix of joint classification probabilities is quasi-symmetric, and that the symmetric matrix component is non-negative definite. The degree of distinguishability between two categories is defined and is used to give a measure of overall category distinguishability. It is argued that the kappa measure of observer agreement is unsatisfactory as a measure of overall category distinguishability.     

Foster child health care supervision policy

Foster children represent a high-risk group for physical, emotional, and social health problems, yet few federal or state policies explicitly address foster child health. This article reviews foster child health and the legal background for policy, then discusses components of a comprehensive health care supervision program.